From the back of the book:
Designed by the Great Maker Autochthon before the Primordial War, the Alchemical templates inspired the Exalts fielded by the Incarnae against their creators. Yet, during that war, Autochthon heard the Great Curse directed by his slain Primordial brethren. As the First Age progressed, he watched as that Curse twisted the minds of the Exalted. Knowing it was only a matter of time before the Solars' growing paranoia was directed at him, the King of All Craftsman gathered thousands of worshipers inside himself and fled to Elsewhere. Within his very body, these mortals built a highly advanced civilization, and to preserve it, Autochthon finally built his prototype Champions. Ever since, the artificial Chosen of the Machine God have kept the Eight Nations safe.
But as the long-dormant Autochthon's health deteriorates, the threats the Alchemicals face grow ever greater. Can these Exalted save their world-god, or has Autochthon's flight to Elsewhere only ensured his demise?
A character sourcebook for Exalted featuring:
Everything players and Storytellers need to generate Alchemical Exalted characters, including their Charms
Details of the Great Maker's servants: the gods, elementals and automata of Autochthonia
Rules for Autochthonian magitech and Alchemical protocols